The following is a letter written by Pope Gregory I to Bishop Mellitus, who was going to join Augustine of Canterbury's mission to the English, giving instructions for dealing with the holy places of the newly converted Saxons and their pagan practices.

Tell Augustine that he should be no means destroy the temples of the
gods but rather the idols within those temples. Let him, after he has
purified them with holy water, place altars and relics of the saints
in them. For, if those temples are well built, they should be converted
from the worship of demons to the service of the true God. Thus, seeing
that their places of worship are not destroyed, the people will banish
error from their hearts and come to places familiar and dear to them
in acknowledgement and worship of the true God.
Further, since it has been their custom to slaughter oxen in
sacrifice, they should receive some solemnity in exchange. Let them
therefore, on the day of the dedication of their churches, or on the
feast of the martyrs whose relics are preserved in them, build themselves
huts around their one-time temples and celebrate the occasion with
religious feasting. They will sacrifice and eat the animals not any
more as an offering to the devil, but for the glory of God to whom,
as the giver of all things, they will give thanks for having been satiated.
Thus, if they are not deprived of all exterior joys, they will more
easily taste the interior ones. For surely it is impossible to efface
all at once everything from their strong minds, just as, when one
wishes to reach the top of a mountain, he must climb by stages
and step by step, not by leaps and bounds....
Mention this to our brother the bishop, that he may dispose of the matter
as he sees fit according to the conditions of time and place.